The environment that outboard motors operate in places special demands on the construction of the motors. Such motors require a sufficient amount of air inside the motor cowl to operate efficiently. One or more paths must therefore be provided for entry of air into the motor.
Unfortunately, such air paths also provide a potential entry point for water which has a detrimental effect on the operation and longevity of the engine. Operation may be adversely affected since water entered into the engine combustion system through an air path can cause the engine to lose power, sputter and stall. The life of the engine may be compromised since water, particularly salt water, drawn into the motor can cause corrosion of the motor over time.
Over the years, many techniques have been employed to address these particular problems. As an example, the basic configuration of outboard motors recognizes these difficulties. Typically, designs for all outboard motor place the engine in a power head formed by a casing referred to as a cowl. The cowl and encased engine are mounted to a watercraft so as to be held above water level. A separate casing attached to the cowl extends below the power head into the water and includes a drive shaft and propeller operatively connected to the engine within the power head. The cowl generally includes one or more inlets through which air enters for use by the engine.
The cowl, motor and air inlets are generally designed to be kept above water level to prevent the entry of water into the air inlets. However, even in that case, operation of the watercraft often results in waves and splashes of water to impinge upon the cowl and associated air inlets.
The splashing of water into cowl air passages is especially prevalent in outboard motors having rearward opening air passages, e.g., passages facing away from the watercraft. Sudden slowing of the watercraft in a body of water often results in a wave of water directed at the rear portion of the motor. This wave, commonly referred to as splash back, may direct water into the air passage.
Similarly, sudden acceleration or turning of a watercraft tends to force the rear portion of the water craft downward. In this situation the outboard motor, typically mounted to the rear of the craft, is lowered in an angled fashion toward the water level. Thus, the rearward portion of the cowl is brought in close proximity to, or even partially submerged below, the water level.
Forward facing portions of the cowl are less likely to become submerged, but may also be subjected to water splashing. Operation of the watercraft in a forward direction may induce spray and splashes which could enter into a forward facing air passage. Thus, while forward facing air passages reduce some risk of water entry, protection of the air passage is sill necessary.
Among the ways to protect both forward facing and rearward facing passages are use of a labyrinth or a baffle which serves to separate the air from water entering through an air passage. Examples of the labyrinth, formed by opposing partition plates, and baffle arrangements are provided in U.S. Pat. Nos. 5,181,870 (Arai et al) and 4,952,180 (Watanabe et al.), for instance.
Complex labyrinth arrangements may be effective in preventing water from entering through the air passage. However, such arrangements may overly restrict the amount of airflow into the engine thereby reducing horsepower output of the motor.
Simpler baffle arrangements have the advantage of better airflow. However, even though a baffle is successful in separating water from air, water may still enter into the cowl. If a path is not provided for exit of the water, accumulation may occur leading to corrosion and other problems. Addressing the accumulation problem, drainage techniques have been proposed in the prior art. Examples of cowls including means for draining separated water are shown in U.S. Pat. Nos. 5,328,395 (Oishi), 5,181,871 (Hiraoka et al.), and 4,723,927 (Walsh et al.).
Typically, as demonstrated in those patents, drainage is provided at a level below the air inlet on the outer portion of the cowl. After water is separated from air taken in through an inlet, the force of gravity is relied upon to drain the water through an appropriate exit. Of course, lower mounted openings in an outboard motor present greater opportunity for water entry because of spatial proximity to a water line. Extreme sloping may be used to prevent much splash entry through a drain opening, but in the case of partial submersion of the motor, water may enter through the drain passage.
In sum, there is a need for an improved cover for an outboard motor which simultaneously permits good airflow, separates air from water entering through an air passage, provides an exit for accumulated separated water and prevents entry of water through the exit. It is therefore an object of the present invention to provide an improved cover for an outboard motor which simultaneously performs those functions.
It is another object of the present invention to provide an improved cover having a generally hollow shell with an air passage, a diverter which diverts water entering the air passage into a collection chamber, and a discharge which discharges diverted water from the collection chamber.
Yet another object of the present invention is to provide an improved cover having an air passage at an upper portion of a hollow shell, a diverter which diverts water entering the air passage into a collection chamber, and a discharge which discharges diverted water from the collection chamber.
Still another object of the present invention is to provide an improved cover for an outboard motor which separates, diverts and discharges water entering an air passage and may be mounted to an existing outboard motor cowl.
A further object of the present invention is to provide an improved cover for an outboard motor which separates, diverts and discharges water entering an air passage through an exit and which prevents entry of water through the exit thereby allowing the motor to operate in a semi-submerged state.